Re: Doubt on defined-ness

while (<FH>) ...
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is the same as doing

while ($_=<FH>) ...
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Not quite. while (<FH>) is shorthand for

while (defined($_ = <FH>))
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Which should clear up the other half of your confusion.

Unless I state otherwise, all my code runs with strict and warnings

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Re^2: Doubt on defined-ness by waldner (Beadle) on Jun 18, 2008 at 19:25 UTC
The camel book lists the following (among others) as being equivalent: `while (defined($_=<STDIN>)) ... while ($_=<STDIN>) ... while (<STDIN>) ...` [download] so I guess that only in the case of a while both the second and third form are equivalent to the first. This is not true for other boolean context like eg if.	[reply] [d/l]
Re^3: Doubt on defined-ness by FunkyMonk (Bishop) on Jun 18, 2008 at 19:41 UTC
It seems perl applies its magic test for definedness to any while that involves a filehandle (at least, I couldn't find a case where it didn't apply). `$ perl -MO=Deparse -e 'while (<>) {} while ( <ARGV> ) {} while ( $_ = +<> ) {} while ( $x = <> ) {}' while (defined($_ = <ARGV>)) { (); } while (defined($_ = <ARGV>)) { (); } while (defined($_ = <ARGV>)) { (); } while (defined($x = <ARGV>)) { (); } -e syntax OK` [download] Unless I state otherwise, all my code runs with strict and warnings	[reply] [d/l]
Re^4: Doubt on defined-ness by ikegami (Patriarch) on Jun 18, 2008 at 22:54 UTC
That's almost the limit. Anything more complex doesn't add a `defined`. `>perl -MO=Deparse -e"while (<FILE> && foo()) {}" while (<FILE> and foo()) { (); } -e syntax OK` [download]	[reply] [d/l] [select]